Various embodiments of a fluid sensor are described herein. In particular, the embodiments described herein relate to an improved superheat sensor.
There are many fluid system applications that require knowledge of a fluid's superheat in order to optimize the state of the fluid system. These systems include, but are not limited to, HVAC systems. Fluids that may be used within these systems include, but are not limited to, refrigerants.
As used herein, the term superheat is defined as the condition where the fluid, regardless of the system type, has excess energy relative to the fluid's boiling point. This excess energy may be measured as the number of degrees of temperature above the fluid's boiling point, or superheat.
Methods of measuring superheat are known. For example, U.S. Pat. No. 5,070,706 discloses a superheat sensor having a single coupling to a fluid channel carrying fluid through which superheat is being measured.
U.S. Pat. No. 5,820,262 discloses a refrigerant sensor for calculating a superheat value for refrigerant material. The sensor has an internal pressure sensor and an internal temperature sensor.
U.S. Patent Publication No. 2011/0192224 discloses a superheat sensor having a flexible wall that defines an interface between an inner cavity having a charge fluid therein and the flow channel in thermal contact with the fluid flowing therein. The flexible wall is adapted to conduct heat between the flow channel and the inner cavity.
U.S. Patent Publication No. 2011/0222576 discloses a method for calibrating a superheat sensor.
Typical superheat sensors do not provide automatic fluid-type detection, high sensitivity, and resolution under a wide range of pressures, store superheat and related parametric history, generate alarms, and provide a variety of industry standard reporting options.
Accordingly, there remains a need in the art for an improved sensor and method of identifying and measuring superheat in fluids, especially refrigerants in HVAC systems.